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United States Patent | 5,548,487 |
Brabetz ,   et al. | August 20, 1996 |
A flat circuit module assembly includes a circuit board and unpackaged, or housingless, chips mounted on its surface, with an elastic pressure pad between the circuit board and the chips. To achieve an adequate spring characteristic, the elastic pressure pad is dimensioned to be correspondingly thick, the consequence of which is that the Z bend of the terminal legs would be greater than would actually be needed for compensating for the thermal stress. To avoid this disadvantage, the invention provides depressions on the circuit board surface into which the pressure pads are placed. This reduces the tolerance range in the surface soldering area. The invention also provides that the circuit board is a multilayer board that has internal conductors, and further that the depression into with the pressure pad is placed extends to one of the internal conductive layers.
Inventors: | Brabetz; Berhard (Unterhaching, DE); Wessely; Hermann (Munchen, DE) |
Assignee: | Siemens Nixdorf Informationssysteme Aktiengesellchaft (Paderborn, DE) |
Appl. No.: | 064081 |
Filed: | May 17, 1993 |
PCT Filed: | September 7, 1992 |
PCT NO: | PCT/DE92/00754 |
371 Date: | May 17, 1993 |
102(e) Date: | May 17, 1993 |
PCT PUB.NO.: | WO93/06703 |
PCT PUB. Date: | April 1, 1993 |
Sep 27, 1991[DE] | 9112099 U |
Current U.S. Class: | 361/769; 257/713; 257/718; 257/719; 257/E21.511; 257/E23.078; 361/707; 361/709; 361/713; 361/717; 361/718; 361/719 |
Intern'l Class: | H05K 007/02; H05K 007/06; H05K 007/20; H01L 023/36 |
Field of Search: | 174/252,138 G,166 R,166 S 257/678,706,707,713,718,719,726,727,717 ;809;705;720;717 361/707,709,710,713,715,718,719,760,761,767,768,769,770,771,772,773,776,807,808 437/209,215,216 |
3225262 | Dec., 1965 | Myers | 174/138. |
4833570 | May., 1989 | Teratani | 361/770. |
4855869 | Aug., 1989 | Tsuji | 361/713. |
5184211 | Feb., 1993 | Fox | 257/706. |
5389819 | Feb., 1995 | Matsuoka | 257/727. |
Foreign Patent Documents | |||
0191270 | Aug., 1986 | EP. | |
0226042 | Jun., 1987 | EP. | |
0338447 | Oct., 1989 | EP. | |
2586885 | Mar., 1987 | FR | 361/713. |
60-257533 | Dec., 1985 | JP | 257/727. |
63-117431 | May., 1988 | JP | 257/678. |
5-109915 | Apr., 1993 | JP | 257/727. |
5-283550 | Oct., 1993 | JP | 257/727. |
2252451 | Aug., 1992 | GB. | |
PCT/JP91/01006 | Jul., 1991 | WO. |
IBM Technical Disclosure Bulletin "Heat Sink Assembly for TAB-Mounted Devices" vol. 31 No. 6 Nov. 1988. |